Current-converting device.



A. R. BULLOCK. CURRENT CONVERTING DEVICE. APPLICATION FILED AUG-18.1913- Patented N 0v. 14, 1916.

A. R. BULLOCK. CURRENT CONVERTING DEVICE.

v APPLICATION FILED AUG. 18, I913. 1 3j4 Patented Nov, 14, 1916.

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\ ARTHUR R. BULLOCK, 0F CLEVELAND, OHIO, ASSTGNOR TO HENRY C. LEE,TRUSTEE,

DE LOS ANGELES, CALIFORNIA.

CURRENT-CONVERTING DEVICE.

Specification of Letters Patent.

Patented Nov. 14, 1916.

Application filed August 18, 1913. Serial No. 785,242.

To all whom it may concern Be it known that I, ARTHUR R. BULLOCK,a'citizen of the United States,'residing at Cleveland, in the county ofCuyahoga and State of Ohio, have invented a certain new;

and useful Improvement in Current-Converting-Devices, of which thefollowing is a full, clear, and exact description.

This invention relates to a device for converting electric current,either alternating current to direct current, orvice versa.

Theobject of the invention is to provide a machine which by the use ofcertain adjuncts may be operated with practically no sparking.

Generally speaking, the invention comprises the elements andcombinations thereof set forth in the accompanying claims.

Reference should be had to the accompanying drawings, in which- Figure'l is a top plan view of one form of the machine; Fig. 2 is an endelevation with portions in section; Fig. 3 is a diagrammaticillustration of the manner in which the parts of the machine cooperatein one form of my device; Fig. 4 is a diagrammatic illustration of theelectrical connections in one form of machine; and Fig. 5 is a diagramof the electrical connections in another form of my invention.

Devices of the general construction which is represented in thisapplication wherein a rotating body with conducting segments thereon isemployed in a manner such that the segments in cooperation with portionsbearing thereon will rectify alternating current, or vice versa, havebeen open to the serious objection that at the time of the break betweenthe brush and the segments on which they bear as the segments are r0-tated, there is considerable sparking which if not prevented may cause alarger arc to be set up, and flashing over between adjacent segments.With a machine which is handling currents of high value, an areestablished in this way will do considerable damage to the machine andin other ways.

In this application, I am proposing one way in which-the sparking andarcing may be reduced to a minimum and substantially eliminated.

I will explain the machine as adapted to rectify an alternating current,although it will be apparent that a direct current may be changed to analternating current with this same machine.

When an alternating current is to be changed to a direct current, Iemploy a synchronous motor, which may be represented at 1. Upon anextension of the motor shaft there is mounted a rotating body 2 carryingconducting portions 3, 4, 5 and 6. These conducting portions or segmentsare made up of a number of small segments, which segments are allelectrically connected to each other, save one, which willlater beexplained. The reason for making the conducting portions of a number ofsegments is simply for reasons of construction, and so far as theelectrical features of this machine are concerned, the conductingportions 3, 4, 5 and 6, might as well be a single conducting strip.

The space upon the commutator between the conducting portions 3, 4, 5and 6, is electrically dead, and might well be constructed of insulatingmaterial. However, in order to secure an even wearing of the surface ofthe commutator by the brushes passing over the commutator, I prefer toemploy segments of copper which are spaced apart by mica insulation, asis the usual construction, and so arrange these segments that they shallnot form any conducting portion of the segment.

Adjacent each conducting portion 3, 4, 5, 6 are segments 7, 8, 9 and 10which are spaced from the conducting portions by means of an insulatedspace, which insulated space is. of less width than the brush whichbears upon the segments so that as the brushes pass from the conductingportions, they will short circuit the conducting portions with thesegments 7, 8, 9 or 10 as the case may be, according to the conductingportion with which the brushes have been in engagement. It should bementioned that I have employed four conducting portions and that theopposite conducting portions are electrically connected, as indicated inFigs. 2 and 5.

Brushes 3 4 5, and 6, are mountedin suitable supports, which supportsare carried upon rings 3", 4 5, and 6 which ringsare frictionally orotherwise held upon an annular projection 1 which is carried by themotor casing.

As will be seen by reference to'the diagram in Fig. 5, I employcondensers represented at 11, 12,13 and 14, which condensers areconnected in parallel withthe conducting portions 3 4, 5 and 6, andtheir adjacent segments 8, 9 and 10. It will therefore be apparent thatas the conducting portions rotate, and the brushes pass from theconducting portions to engage with the segments 7, 8, 9 and 10, asbefore explained, the brushes will connect the conducting portions andthe adjacent segments. Therefore, as the current is broken between thebrush and the conducting portion, there will be a con denserelectrically connected in parallel with the break in the circuit betweena brush and the conducting portion upon which ithas borne, so that anycurrent which would be flowing at the time of the break, Will flow intothe condenser and be absorbed therein.

' and its adjacent segment, and the discharging of the condenser wouldproduce a sparking which would be very detrimental to the segments inthat it would burn them and soar them so that the likelihoodof' arcingat the time of breaking of the circuit .would be greatly increased. Ihave provided means for discharging the condensers sothat each time acondenser is presented to absorb the current, at the time of breakbetween a conducting portion and its brush, it

n will be substantially neutral, and thus in condition to absorbcurrent. This I accomplish by'placing a resistance in parallel with eachcondenser, as represented at 15, 16, 17 and 18. Thisresistance is chosenso that the current flowing at-the time of break between, a conductingportion and brush will pass to the condenser, and not to the resistance.However, as soon as the brush has entirely broken with a conductingportion, it will be seen that the .condenser which has just beencharged, is-practically shortcircuited through a resistance so that thecondenser will discharge itself through this resistance as shown in Fig.5. In other words, the condenser charge is dissipated and the-condenseris thus in condition to receive a subsequent charge. -A condenser orcircuit having capacity which dissipates its charge may be embodied informs other than that herein shown, the only requirement being that whenused in a circuit such as herein shown its function and results shall bethe same. I consider a condenser or c1rcu1t containing capacity, whichis so arranged in a c1rcu1t as to receive and disslpa'te a charge,

as the equivalent of the short circuited condenser herein shown." Ofcourse, in a measure, this current is wasted, but the amount of currentwhich is so expended, is not very large, so that the efliciency of themachine is not greatly reduced, and the loss thus occasioned is morethan compensated by the fact that the machine is operable substantiallyin sparkless condition. These condensers andtheir resistances aremounted upon the shaft which carries the rotatable member 2, V

and are housed within a casing 19. which is also carried upon the shaft.This casing or other air stirring means, such that the condensers andtheir reslstances are cooled as the machine is operated.

Another form'of machine embodying the same principle is illustrateddiagrammatically in Figs; 3 and 4. The machine as represented in thesefigures will be operated by a motor which will be a synchronous moto'r,

in the event that alternating current is changed to direct. will bemounted a rotatable body 20 provided with conducting portions 21, 22, 23and 24, oppositely arranged conducting portions 21, 22, 23 and 24, by ameans similar to that illustrated and described in cons nection withFigs. 1 and 2.

Associated with each brush is an auxiliary brush 25 26 27 and 28?. Eachof these brushes is so positioned with respect to its principal brushthat as the principal brush is just passing from contact with aconducting portion, its auxiliary brush is coming into full contact withthe same conducting portion. Between each principal brush and itsauxiliary brush, there is connected a condenser, the various condensersbeing represented at 29, 30, 31 and 32. Each of these condensers isconnected in' parallel with a resistance 33, 34, 35 and 36.

It will be apparent that in operation, as a principal brush is passingfromcontact with a given conducting portion, any current which may beflowing at the time of breaking, will find a path through the,aux--iliary brush and through the condenser.- In this way, the condenser willbe charged. The resistances in parallel with the-condensers will operatein the same manner as heretofore .described, and will thus alwayspresent a condenser in condition to absorb 90 Upon the motor shaft I 80may be provided with suitable fan blades current at the time of breakbetween a principal brush and a conducting portion. The principalbrushes and their auxiliary brushes will be mounted in a manner similarto that shown in Fig. 1.

As has before been suggested, the device is capable of changingalternating to direct current as explained, or direct current toalternating current. The only difierence in construction incident tousing the device in the two ways mentioned, is that the motor 1 must bea synchronous motor, if alternating current is rectified, whereas, ifdirect current is changed to alternating, an ordinary motor willsuifice.

Having thus described my invention, what I claim is:

1. The combination with an alternating current circuit and a'directcurrent circuit,

; of a device for connecting each side of one of said circuitsalternately with the sides of the other circuit, in combination with acircuit containing capacity adapted to dissipate its charge, whichcircuit is introduced by the aforesaid device between cooperating sidesof the A C and D G circuits at the time the connections between thecircuits are broken.

2. In combination with an alternating current circuit and a directcurrent circuit, of a device for connecting each side of one of saidcircuits alternately with the sides of the other circuit, in combinationwith a circuit containing a condenser adapted to dissipate its charge,which circuit is introduced by the aforesaid device between cooperatingsides of the A C and D G circuits at the time connection between thecircuits is broken.

3. The combination with an alternating current circuit and a directcurrent circuit, of a device for connecting each side of one of saidcircuits alternately with the sides of theother circuit, in combinationwith a circuit containing capacity, which circuit is introduced by theaforesaid device between cooperating sides of the A C and D C circuitsat the time connection between the circuits is broken, and means forcausing the circuit containing capacity to continually discharge itself.

4. The combination with an alternating current circuit and a directcurrent circuit, of a device for connecting each side of one of saidcircuits alternately with the sides of the other circuit, in combinationwitha circuit containing a condenser, which circuit is introduced by theaforesaid device between cooperating sides of the A C and D C circuitsat the time connection between the circuits is broken, and means forcausing the condenser to discharge.

5. The combination with an alternating current circuit and a directcurrent circuit, of a device for connecting each side of one of saidcircuits alternately with the sides of the other circuit, in combinationwith a circuit containing a condenser, which circuit is introduced bythe aforesaid device between cocperating sides of the A C and D Gcircuits at the time when the circuit is broken, and means fordischarging the condenser as soon as it becomes charged.

6. A device for converting current comprising conducting portions,brushes bearing upon said conducting portions, a circuit containingcapacity adapted to dissipate its charge, and means for connecting thesaid circuit between a brush and the conducting portion over which thebrush is passing at the time of break.

7. In a device for converting current, comprising a body provided withrotatable conducting portions, brushes adapted to bear upon the saidconducting portions, a circuit containing. a condenser adapted todissipate its charge, and means for connecting the said circuit betweena brush and with a segment over which the brush is passing at the timeof break.

8. The combination with an alternating current circuit and a directcurrent circuit, of a device for connecting each side of one of saidcircuits alternately with the sides of the other circuit, of a circuitcontaining a condenser, which. circuit is introduced by the aforesaiddevice between co'ciperating sides of the A C- and D C circuits at thetime connection between the circuits is broken and a resistance inparallel with and connected at opposite ends of the condenser.

9. A device for converting current comprising conducting portions,brushes bearing upon said conducting portions, a circuit containing acondenser, a resistance in parallel with and connected to opposite endsof the condenser, and means for connecting the said circuit between abrush and a con- -"ducting portion over which the brush is passing atthe time of break.

In test1mony whereof, I hereunto aifix my signature in the presence oftwo witnesses.

ARTHUR R. BULLOCK. -Witnesses A. J. HUDsoN, L. I. PORTER.

